In this study, cellulose pulp and urea were used to synthesize cellulose carbamate (nitrogen content reaches 4.5%) by low-cost and environmentally friendly solid-liquid phase method. Cellulose carbamate fluid was prepared by using sodium hydroxide aqueous solution as solvent. The fluid was regenerated and formed in a coagulation bath , and finally a regenerated cellulose membrane with high transparency and separation ability was obtained. The simple chemical treatment of cellulose not only greatly increased the mass fraction of cellulose dissolution (It has reached 15%) and retains the original crystal form and thermal stability of cellulose. The surface of the membrane was relatively dense, and the inside has regular microchannel . The factors affect the transparency and water flux of regenerated cellulose membranes were discussed by orthogonal experimental range analysis. The ability of the regenerated cellulose membrane to reject dyes was tested. The results showed that the rejection of methyl blue and congo red reached 100%, and the rejection rate of methyl orange reached 60%. The oil/water separation ability and the anti-pollution ability of the regenerated cellulose membrane were tested. The oil/water separation effect reached 100%. This membrane may have application prospect in water treatment, biotechnology.
Yingying Meng,An Li,Huan Li,Zhensheng Shen,Tian Ma,Jiuyi Liu,Zhongze Zhou,Qian Feng,Yingqiang Sun
Membrane blocking is of great importance to nutrients transfer and illumination in attached cultivation of algae, which subsequently affects the biomass and nutrients production of algal biofilm . Accordingly, a vertical-algal-biofilm (VAB) with cellulose acetate (CA) membranes with pore size of 0.45, 1.2, 2.0, and 3.0 μm is settled to study the effect of membrane blocking on attached cultivation of microalgae . According to the results, the algae production is independent of the roughness, hydrophilicity , and surface free energy of membranes because the VAB is inoculated via filtration-on method in this work. Nevertheless, the algae productivity of first-cultivation on VABs increases to 5.02 g/m 2 . day when the pore size of CA membrane increases to1.2 μm, while it decreases to 4.5 g/m 2 . day on VABs with CA-3.0 due to the complete blocking of CA membranes by algae cells. The growth rates of first-cultivation and re-cultivation are well fitted by a logistic model and a linear model, respectively. The total lipids contents of microalgae on different CA membranes are affected by pore size due to the variations of nutrients transfer resistance and light intensity under different membrane blocking models. A maximum total lipids content of algae biomass cultivated on VABs with CA-1.2 is about 23.74% due to the nitrogen starvation and high illumination intensity under intermediate blocking model. Therefore, the attached cultivation of algae on VABs under intermediate blocking model is much favorable for algal biomass and lipid production.
Xuliang Lin,Xueqing Qiu,Duming Zhu,Zihao Li,Ningxin Zhan,Jieyi Zheng,Hongming Lou,Mingsong Zhou,Dongjie Yang
Effect of the molecular structure of lignin-based polyoxyethylene ether (EHL–PEG) on enzymatic hydrolysis of Avicel and corn stover was investigated. With the increase of PEG contents and molecular weight of EHL–PEG, glucose yield of corn stover increased. EHL–PEG enhanced enzymatic hydrolysis of corn stover significantly at buffer pH 4.8–5.5. Glucose yield of corn stover at 20% solid content increased from 32.8% to 63.8% by adding EHL–PEG, while that with PEG4600 was 54.2%. Effect of EHL–PEG on enzymatic hydrolysis kinetics of cellulose film was studied by quartz crystal microbalance with dissipation monitoring (QCM-D) and atomic force microscopy (AFM). An enhancing mechanism of EHL–PEG on enzymatic hydrolysis kinetics of cellulose was proposed. Cellulase aggregates dispersed by EHL–PEG excavated extensive cavities into the surface of cellulose film, making the film become more loose and exposed. After the maximum enzymatic hydrolysis rate, the film was mainly peeled off layer by layer until equilibrium.
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